1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method using an image pickup device, such as a charge-coupled device (CCD) and, in particular, to a pixel defect correction technique for the image pickup device.
2. Description of the Related Art
The importance of pixel defect correction in the image pickup device is mounting along with high-definition design implemented in the image pickup device for electronic still cameras or video cameras. A variety of techniques for correcting image degradation attributed to an image output from a defective pixel are known. Most of the known techniques correct a defective pixel based on pixel defect information (representing the location of and the defect level of a defective pixel) of the image pickup device collected before the shipment of the image pickup device.
The known techniques are unable to perform sufficient pixel defect correction because no defect information is updated concerning a defective pixel that has escaped detection performed before shipment and a defective pixel taking place as a result of aging.
Several techniques have been proposed to overcome this problem. For example, according to Japanese Patent Laid-Open No. 8-18873, a video camera has a defective pixel detection mode for detecting a defective pixel of an image pickup device. Defective pixel location data detected during the detection mode is compared with defective pixel location data stored in a memory, and information concerning a new defective pixel only is added to the memory for correction.
According to Japanese Patent Laid-Open No. 8-18873, if defective pixel location data detected during the detection mode matches defective pixel location data stored in the memory, no new defective pixel is added in the memory. No pixel defect level information updating is performed concerning a defective pixel that was detected at the shipment and further degraded in the pixel defect level subsequent to the shipment. Since the defective pixel detection is not performed with a desired pixel defect detection level range selected, pixel defect data more than necessary is collected, thereby consuming a large amount of memory space.